Key-responsive cycle initiating mechanism



Sept. 26, 1961 J. B. POW 3,001,700

KEY-RESPONSIVE CYCLE INITIATING MECHANISM Filed Sept. 6. 1957 4 Sheets-Sheet 1 NVEN HIS ATTORNEY Sept. 26, 1961 V J. B. POW 3,001,700

KEY--RESPONSIVE CYCLE INITIATING MECHANISM Filed Sept. 6. 1957 4 Sheets-Sheet 2 HIS ATTORNE! INVENTOR ES BOVAIRD POW Sept. 26, 1961 ow 3,00L700 KEY-RESPONSIVE CYCLE INITIATING MECHANISM Fild Sept. 6, 1957 4 Sheets-Sheet a FIG. 5

E TOR INV N JAMES BOVAIRD POW His ATTORNEY p 1961 J. B. POW 3,001,700

KEY-RESPONSIVE CYCLE INITIATING MECHANISM Fild Sept. 6, 1957 4 Sheets-Sheet 4 FIG. 8

VENTOR JAM BOVAIRD POW Hns ATTORNEY and return mechanism associated therewith.

United States Patent 3,001,700 KEY-RESPONSIVE CYCLE INITIATING MECHANISM James Bovaird Pow, Tayport, Fife, Scotland, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed Sept. 6, 1957, Ser. No. 682,390

4 Claims. (Cl. 235-62) This invention relates to accounting and similar calculating machines, and more particularly to the type of machines wherein the digit keys are partially depressible for determining entries into the machine and fully depressible to cause the machine to execute a cycle of operation. V

-It is known to provide electro-mechanical arrangements insuch machines which, when a digit key is fully depressed, cause the closure of a switch to complete a circuit to an electromagnet which, through a mecha'nical linkage, causes closure of a circuit to an electric driving motor and the opening of said switch to break the circuit to the electromagnet.

However, such electro-mechanical arrangements require very precise adjustment, are costly to manufacture, and also necessitate the inclusion in the circuit to the electromagnet of electrical interference suppressing dev1ces.

An object of the present invention is to provide simple, cheap to manufacture, and reliable mechanical arrangements whereby a machine cycle may be initiated byfull depression of a digit key. 7

A further object of the invention is to provide mechanical arrangements whereby, whendesir ed, the initiation of machine cycles by full depression of a digit key may be disabled.

A still further object of the invention is to enable the conversion of machines, including electro-mechanicaldigit key operated machine cycle initiating arrangements, to mechanical digit key operated machine cycle initiating arrangements, with the minimum of modification and addition to existing parts. f a

With these and other objects in view which will become apparent from the following description, the invention. includes certain novel features'ofv design'a-nd 'combinations of parts, a preferred form or embodiment'of which is hereinafter described with reference to the drawings which accompany and form a part of this specification. v a

. In the drawings: ,V

FIG. 1 is a schematic perspective view ofthe machine 3,001,700. Patented Sept. 26, 1961 ice struction to that shown in United States Letters Patent No. 2,745,601, issued May 15., 1956, to Roland G. Fowler et al., and includes a keyboard consisting of a number of denominational rows or banks of digit keys. The units keybank is partially illustrated in FIG. 1, that is, the keys appertaining to the digits one, two, three, and nine, and are designated 1, and it is to be understood that these keys are typical of all of the keys in said bank, and that all banks are similar. As in the aforementioned United States Letters Patent, all the digit keys of the keyboard have a dualmode of depression, that is, they are partially depressible to a latching position in which they are latched to control the settings of differtial mechanisms for elfecting, inter alia, the entry of amounts into a total-izer (not shown), according to the set-up of the depressed keys, during an ensuing operating cycle of the machine, the keys being automatically released to return to normal position at sometime after the differential mechanisms have been set.

The second mode of operation of the digit keys is constituted by a further, or full, depression thereof beyond the latching position, and against additional tension, a fully depressed key returning to the latching position when manual pressure is released therefrom. The depression of any digit key to this position of full depression initiates an operating cycle of the machine.

The digit keys 1 (FIG. 8) of a particular row are nine in number, each having a keystem 100 slidably mounted in alined slots in an upper support plate 101 andin a lowor support plate 102, which form part of the keyboard framework. Each key is kept in a normally undepressed position by an associated spring 113 extending between plate 102 and a formation on the keystem, so that pressure applied to a key pushes it down. When a key is pushed down to a latching position, a formation thereon is engaged by a latching bail 103 resiliently held against all the keys of a row. .There is a latching bail for each row of keys, each bail being pivoted in end plates 104 and 114 of the keybank unit. Pivoted on a rod 7, to be described later, which rod runs across the front of the machine, is a key release bail 105, which may be rocked around rod 7, so that fingers thereon, which extend rear,- wardly alongside the latching bails, may move the latching bails to ineffective position, such rocking being brought about by downward pressure on a stud 106 secured to a rearwardly-extending arm of bail 107. The

latching mechanism described is more fully disclosed cycle initiating mechanism and the restoring mechanism FIGJS shows a portion of the mam driving mechanism left of the machine,

' of the machine.

FIG. 6 is a detail'view of part of the mechanism of FIG. 1. FIG. 7 is a right-side view of the electric driving motor and its clutch control mechanism.

FIG.'8 is a vertical section'throu'gh the keyboard, from front to rear, showing a typical key-bank row, the differential mechanism therefor, and part of the key release F1G.,, 9 is an elevation of the .right side of the keyboard unit and the cyclically-operated means to release the keys, The machine shown in the drawings is of similar conin the aforementioned United States Letters Patent. In addition to the latching mechanism, each bank of keys is provided with a slide plate 2 which passes through apertures 3 in all of the keystems of the bank, and adjacent each keystem has a camming surface 4. During the de-.

pression of a key to its latching position, the upper bound ing surface of the aperture 3 does not coact with the. cooperating camming surface 4, and, therefore, the slide plate 2 is not affected. However, on the depression of a key to its fully depressed position, the upper bounding surface of the aperture 3 engages the camming surface 4 to cause a forward movement of the slide plate 2.

Each of the slide plates 2 at its front end, that is the left-hand end in FIG. 1, has a dependent finger 5 which engages in a slot in a motor operating bail 6 which extends across the front of all of the banks of keys and is pivotally supported on the rod 7 by brackets upturned from said bail, the rod 7 being secured by screws 8 (only one shown) to the side frame of the keyboard assembly, part only of the right-hand keyboard side frame 9 being shown in Fig. l. The bail 6 has applied thereto a counter-clockwise tension from a spring 6a which thus tends to maintain the slide plates 2 in their rearward positions, and also causes the latter to assist in returning a key from the position "1'7 projecting laterally therefrom between which on the lever '11 normally to maintain the hook engagement with the latch-plate 10.- a

which, as seen'in FIG..,3, is

of 'full depression to the latched position on the release ofmanual pressure from the key.

The keys are'operable to the latching position against ,the tension of the light spring Y113) and it will be apprethat the operator may stop at this degree of depression if his not desired to initiate an operating cycle of the lmachine. The tension applied tothe bail 6 may bevariable by providing for the adjustment ofthe spring 6a associated therewith to suit the operating touch of the operator. p p The motor operating bail .6 has integral therewith a fdownwardly extending latch plate 10 adapted normally to engage with a hook on one arm of a three-armed lever 11 (see also FIG. 6) pivotally mounted on a screw 's'tud 12 secured in a right-side frame 13 of the machine, only a part of said frame 13 being illustrated in FiG. l. The screw stud 12 also forms the pivot for amultharmcd trip lever 14, the latter being spaced apart from'thethreearmed lever 11 by a spacing collar 15. A downwardly extending arm 16 of the three-armed lever 11 has a stud a stud 18, secured .111 the right side frame 13, is tensioned one or more springs such as 19 which exerts a clockwise pressure thereof in A laterally extending lug 2%? on the arm of the niultiarmed triplever 14 overlies the central arm. of: the lever 111,. and is maintained in contact therewith by tension exerted by a spring 21 secured between'the lug 20 and the Stud 18.

fl'he end of the stud 17 engages with a slot '22 at the *left hand end of a link 23. Undennormal circumstances, the stud 17 is located at, a short distance from the lefthand boundary of the slot 22 to allow a free movement of the stud towards the left, aswill be described later. )The other end of the'link '23 is pivoted to an upstanding arm of an L-shaped lever 24pivoted on a screw stud 26 engaging in the frame 13, and a rearwardly extending limbof the lever 24 carries a roller stud 27which cooperates with acam plate 28 secured to a full stroke sector 29' secured to the right-hand end of a front shaft 39 which, during an operating cycle ofthenrachine, is adapted to be 'reciprocated counter-clockwise and back, over an angle or" approximately 90 degrees, from a main driving shaft through the medium of a crank, as explained later. g

M The central arm of the three-armed lever 11 is provided I with a oam slot 31 and pivoted on a screw stud 32 secured in the right-hand sideeframe 13 of the machine is an fOn and DE lever 33. 'Ihelever 33: has a pin '34 therein which,. '-when the'lever33 is moved'clockwise to ft 7 position, engages in the cam slot 31 to cam the *lever 11 slightly counter-clockwise. I i

urgency of the spring 47 by an car 49 of the bell-crank 44 v roller 51 of insulating material which cooperateswith a moving spring of a cantilever switch 52 connected serially in the circuit of an electric machine driving motor 53,

showndiagrammatically-in FIG. 3 and illustrated in FIG.

7. The switch '52 is normally open, and the moving spring thereof, through the roller 51, normally exerts a counterclockwise pressure on the lever 50 to-maintain. the lower end thereof in contact witha stud 54in the depending arm of the bell-crank 44. The upper end of the lever 50 is provided with an car 55 with which. a latch pawl 56,

pivoted on the left side frame 43 of the machine, is

adapted to cooperate to latch'the switch 52 closed throughout an operating cycle of the machine once an operating cycle has been'initiated. 7

When any one ofthe keys 1 is depressed to its fullest extent, the associated slide plate 2 is moved florwardly, and, throughits dependent finger rocks t-he'bail 6 clockwise as seen in FIG. 1, to disengage the latch plate from the hook of the lever 11.

11 is released it makes a clockwise movement, and imparts a similar movement to the trip lever. 14, through Q hand boundarythereof. The dependent: arm of the trip lever 1.4 moves the link 36 forwardly, as viewed in FIGS. 1 and 2, to rotate the lever 37 counter-clockwise whereby its end moves forwardly, as viewed in FIG. 2, or to the left as viewed in FIG. 3. Inthis latter movement, the

end 40 of'the lever 37 (FIG. 3) shoves-the trip 'latohdl clockwise which de-latches its step from the ear 49 of the bell-crank :44, allowing the latter to be pulled clockwise by the spring 47, andto-impant a similar-movement to the lever. 501 through the stud 54. The roller stud 51 on the'lever 50, therefore, moves to the right to press the springs of the switch 52 into contact to close thecircuit to the motor 53. At the same time, a stud 57' on the lever trips a clutch mechanism which will now'be desoribed.

The clutch mechanism is mounted on a main drive shaft 58is a crank plate 60' having pivoted thereto, at 61, t

a pawl 62 which is urged ina counter-clockwise direction by a: spring 63 so that atooth on said pawl is adapted to beengaged' with one of the notches of the notched wheel 59 to "couple the. latter to the plate 69 sothat, when coupled, the plate 60 and the shaft 58 may be driven in V unison by the motor 53. When the machine is at rest,

The depending arm of the trip lover 14 has its end bent over to'form a horizontal lug 35 to which is pivoted one-end of a rearwardly extending link 36 (see also FIG.

thereof, and mounted on a stud 42in a left side machine frame-43, partially illustrated in FIGS. -1 and 7. A bell crank lever 44 is secured bya bush to a three armed lever 45 (see also FIG. 7), and the assembly is mounted on a shaft 46, a spring 47, secured between the three armed lever and a stud 43 in the frame 43, exertinga clockwise 7 pressure as seen in FIG. 3 on the assembly which, however, is normally restrained against movement under the the stud 57 on the lever 45 rests against the upper end of the pawl 62, holding it in a clockwise direction, against the urge'of the spring 63, so that the tooth of the pawl 62 does not engage in any one of the notches in the notched wheel 59. V

However, when the trip latch 41 (FIG. 3) is moved clockwise, as described above, toinitiate a machine cycle,

the lever 45 (FIG. 7) is rocked counter-clockwise to are move the stud 57 fromthe upper. end of ,the pawl 62, thereby enabling thespring 63 to engage the tooth onsaid pawl 62 in one of the notches of the. notched wheel 5.9. As. described, movement of the-trip latch 41 (FIG. 3) clockwise closes the switch 52 to energize the 58, the notched wheel 5.9, and the pawl '62.

Pivoted to the mountedon arear drive'shaft 66. The lever 65 is coupled to the shaft 66 through the medium of .a lever 67 pivoted r '.to the forwardly extending arm of upwardly and rearwardly extending end of the'vleveri6 7 1 mounted thereon a roller 68' adapted to engage a The spring 19 has a. greater tension than the spring 21, so that when the lever motor 53 and drive the crank plate 60 (FIG. 7) through the shaft platefll' is a drive link Git-Which is pivoted, atitsother'end, to a two-armed lever 65-.I1ooscly the lever ,65." The snor /e hotch ins disc 69 secured tothe shaft 66, and is held in engagement with said notch by a strong spring 70. Therefore, as the crank plate 60 makes a counter-clockwise rotation, the shaft 66 is rocked first clockwise, and then counter-clockwise, as seen in FIG. 7, to cause a'cycle of machine operation.

The shaft 66 (FIG. 3) carries a cam 71, having a nose 72, which nose normally holds'the latch pawl 56 in an inoperative position and, ion the initial movement of the shaft 66 counter-clockwise as seen in FIG. 3, the nose 72 moves away from the end of the pawl 56 to allow the latter to descend and latch the ear 55 of the lever 50, thereby to hold the latter in operated position and thus maintain the switch 52 closed. i f Ihe right-hand end of the rear drive shaft 66 has secured thereto a plate 75, having pivoted thereto adrive link 76, which is, in turn, pivoted to the full stroke sector 29', so as to rock vthe latter first counter clockwise and then clockwise, as seenin FIGSfl, 4, and 5, during a machine cycle. a i

After the differential mechanisms of the machine have been set, and during the return movement thereof, the depressed digit keys -1 are automatically released to normal position nearthe end ofthe cycle. As shaft 66 (FIG. 5) rocks plate 75 first counter-clockwise and then clockwise during a machine cycle, so is full stroke sector 29, by link 76, as explained, rocked in, like manner. Referring to FIG. 9, full stroke sector29 supports a stud 8, against which the lower end of a rearwardly and downwardly extending arm of a lever 109, pivoted to the right side of the keybank unit at 110, rests'and against which'it is held, when the machine is at rest, by a spring 111: -As a cycle of machine operation commences, stud 108 moves away from the end of lever 109, which rocks clockwise, a bypass pawl 112 thereon brushing by keyrelease stud106. On the return of full stroke sector 29 to home positiomthe by-pass pawl 1.12. strikes key-release stud 106 solidly, and rockskey-release bail in la key-releasing movement, whereby the latched keys 1 return to .norinal position, all, as explained in greater detail in the before-mentioned- United States Patent No. 2,745,601. The linlcage 36, 37 (FIG. 2) and the trip latch 41 are returned to homeposition, at about the same time, in the following manner. At an instant near the end ofthe machine cycle, a cam 73, formed on the crank plate 60,.engagesa roller 74 on the lever 45 to rotate thelatter clockwise. ('FIG. 7). Clockwise rotation of the lever 45 places the stud 57 in thepath "of a surface of the pawl 62 and rocks the latter clockwise about its pivot :61 to disengage the pawl 62 from the notched wheel 59 thereby disabling the drive of the rear shaft 66. As seen in FIG.'3, counter-clockwise movement of the lever 45 (clockwise as seen in FIG. 7), rotates, the bell-crank 44 also counter clockwise, whereby the rear 49 is raised above thestep of the trip latch 41. Following this, the nose 72 of the-cam 71 engages and lifts the latch pawl 56- Which thus releases the lever 50 to the tension of the moving spring of the switch 52, the latter thereby "rotating the lever 50 counter-clockwise until itslowerend re-engages thestud 54 in the bell crank '44, and also moving out of contact with its coacting spring to open the circuit of the motor 53.

Upon reciprocation of full stroke sector 29, as above described, the cam plate 28 (FIGS. 1, 4 and 5) is also reciprocated counter-clockwise and then back. At about 45 degrees of its counter-clockwise rotation, the high surface of the, cam plate 28 depresses the stud 27 which, therefore, rotates the L-shaped lever 24 (FIG. 1) clockwise. The upstanding arm of the lever 24 pulls the link 23 rearwardly, which picks up the stud 17 and rotates the lever 11 counter-clockwise against the actionof the spring 19. Counter-clockwise rotation of the lever 11 causes the control arm thereof to move downwardly, followed by the trip lever 14, under the action of spring 21. This corresponds approximately to the time when ;the nose 72 (FIG. 3) of the cam 71 raises the latch pawl 56 to allow the lever 50 to restore thereby to'open the switch 52 and disconnect the motor circuit. The hooked arm of the lever 11 moves downwardly to a position below the latch plate 10, thus allowing the latter-to return to latching position in re-engagement with the hook, that is, in the assumption that the fully depressed key has, by this time, been released to allow the bail 6 to return to normal position, which conditions should pre vail in normal operations. At the same time, trip lever 14 (FIG. 1) and trip latch '41 (FIGS. 1 and 3) are rotated counter-clockwise, under urge of spring 21,to relatch car '49 of the bell crank 44.

In FIG. 1, the On and Off lever 33 is shown in On position, that is, it is inoperative and, in consequence, the digit keyboard is motorized. When the lever 33 is moved to the OE position, the pin "34- engages in the cam slot 31 to cam the thr -armed lever 11 slightly counter-clockwise and locks it in this position so that its hooked arm moves downwardly out of contact with the latch plate 10, its central arm moves out of contact with the lug 20, and its lower arm moves the stud 517 along the slot 22 in the link 2-3 to such an extent that it will not be engaged by the forward boundary of the slot 22 on the rearward movement of the link 23 during an ensuing machine cycle. Thus, the lever 11 is disabled so long as the lever 33- remains in the OE position. v

The machine may also be cycled by the normal motor or release bar '77 (FIG. 4), the stem of which is provided with an ear 78 which overlies a stud 79 at one end of a lever 86 pivoted on a stud '81 in the trip lever 14. Also on the same stud is a bell-crank 82 having one arm thereof lying substantially parallel to, and which underlies a stud 83 in the lever 80. The other and upstanding arm of the bell-crank 82 lies substantially paral lel to'a finger projecting upwardlyfrom the trip lever 14 and makes contact with the finger through a lug overturned therefrom, a spring 84- coupling the bell-crank and the trip lever 14 maintaining this contact.- When the motor bar is depressed, the car 78 of itskeystem depresses the stud 79 and rotates the lever clockwise, which imparts a similar movement to the bell-crank 82 through the stud 83. Through the coupling of thebell crank 82 and the trip lever 14, by the spring '84, the latter is caused to follow the former, thus to trip the machine as will be understood from the prior descriptionf What is claimed is;

' -1. In a machine of the class described, the combination or a machine drive means capable of cyclic opera tion for entering data into the machine; an electric motor energizable for driving said drive means through its cycles of operation upon the closing of an electric circuitya machine cycle initiating means operable to close said electric. circuit to energize said motor; a rockable trip lever for operating said machine cycle initiating means; a rockable impact lever axially aligned and operably connected with said trip lever, said impact lever being yieldingly urged from a home position to a second position, in which it will operate the trip lever; a bail member operably associated with said impact lever and being movable from a latching position to an unlatching position in relation thereto, said bail member being yieldingly urged to the latching position for retaining the impact lever in its home position; a plurality of rows of selectively operable digit keys, each key being operable from a home position to a second position for controlling the entry of data into the machine during a cycle of operation of said drive means; means intermediate and connected to the digit keys and the bail member, and operable by the digit keys, so that when any digit key is operated to a second position the bail member is moved to its unlatching position in relation to said impact lever, thereby enabling said impact lever to be rocked from its home position to its second position for operating the trip lever and initiating a cycle of operasaid machine drive means; and means operated bysaid machine drive means for restoring the impact leverto its home position where it is retained .by the bail member; when yieldingly returned'to its latching position upon the release of operated digit keys.

2. .In a. calculating machine having a main drive means capablecf cyclicopcration-for enteringydata into the machine; an electric motor energizable for driving said operating means through its cycles of operation upon the closing of an electric circuit; a machine cycle initiating,

means operable to close said electric circuit to energize said motor; a rotatable trip lever operable for operating said machine cycle initiating means; a plurality of digit keys, arranged in denominational rows, each key being operable against a resistance from a home position to a first position and, optionally, operable further to a secon'd positionagainst an added resistance, said keys in either the first or second position controlling the entry of data into the rn-achineduring a cycle of operation of said drive means; means latching said digit keys when V operated to the first position; and means operated durthereto, said bail member being yieldingly urged to the latching position -for retaining the impact lever in its home position; means interconnecting said digit keys with said baillmember and moving said bail member to its unlatching position in relation to said impact lever when a. digit key is operated to a second position, thereby enabling said impact lever-tobe rotated to its machine tripping position and operate the trip lever forinitiating a :cycle of operation of said drive means; and means extending between'the drive meansand said impact lever for returning said impact lever to itshome position near the end of each cycle of said drive means, whereupon said impact lever is retained in the home position by the bail r member when moved to its latchingposition as the digit .keys return to home position upon release of the latching means therefor. it a 3. The machine of claim 2, including a manually shiftable disabling lever operably associated with the impact lever and having an effective position and "an ineilective position of adjustment in relation thereto; said disabling lever, when shifted to its inelfective position of adjustment, enabling the impact lever to be rotated from its home position to its machine itrippingposition for operating the trip lever upon the operation of a digit key to 'its's'econd position; and said disabling lever, when shifted to its efiecuive position of adjustment, retaining the impact lever in its home position and preventing rotation thereof for operating thetrip lever despite operation of a digit key to its second position.

tion of a machine drive meanscapable of cyclic operationzfor entering data into the machine; an electric motor energizable for driving said drive means throughits cycles of operation upon the closing of an electric circuit; a machine cycle initiating means operable to close said electric circuit to energize said motor; a rotatable trip lever operable from a home position to a second position-in which it will operate said machine cycle initiating means; tension means continuously urging. said gtrip lever to its home position; a rotatable impaotlever op erable from a home position to a machine tripping posi: him, said impactlever being axially aligned and operably connectedwith said trip lever so as .to carry the trip lever therewith, and to its second position when saidimpaot lever is operated from its home position to its machine tripping position; tension means for overcoming said trip lever tension means and continuouslyurging said impact 'lever'to its machine tripping position; a bail member operably associated with said impact lever and. being movable from a latching position to an un1atching position in relation thereto, said bail member being yieldingly urged to its latching position for retaining the impact lever in its home position; a plurality of rows of selectively operable digit keys,'each key being operable from a home position to a first position and, optionally,

operable further to. a second position against an added resistance, said keys in either the first or second position controlling the entry of data into the machine during 7 a cycle of, operation of said drive means; means latching. each of said digit keys when operated to its first position;

means operated during each cycle of said drive means zfor releasing the latching means so that each operated key mayreturn to its home position from the first posi: tion; means intermediate and connecting the digit keys of eachrow with the bail member, said means being .qperable by the digit keys so that when any 'key is operated to itsseeond position the bail member is moved from its latching position to its unlatching position, whereupon the impact lever tension meansrcauses the impact lever to rotate and operatethe trip lever for initiating a cycle.

of operation of said drive means; and means operated by the machine drive means to overcome the impact lever tension means and restore said impact 'lever to its home position where it is retained asthe bail member moves to latching position upon release of the digit key latching means; said trip. lever being then returned to its home position under urge of the tension means associated therewith. g

References .Cited in the tile of this patent V UNITED STA TES PATENTS 1,849,169 Britten Mar. 15; 1932, 2,552,789 Hopkins May .15, 1951 2,654,539 Brubaker one, 19:53

- 2,660,374 Hopkins Nov. 24, 1953' 2,714,988 Brubaker Aug. 9, 1955 2,745,601 Fowler May lS, 1956 2,838,235

Snyder June 10, 1958 UNI ED STATES PATENT EETcE CERTIFICATE OF CORRECTION T Patent No; 3,001300 September 26 1961 James Bovaird Pow Column 2 line 66 for "frame-"Y read frames column 3,, line 25 after which insert and --3 line 3O, for ."the", first occurrence read an line 35 for "with" read "within line 57 for lover read lever -5 same column 3 line 6T for "strip" read trip Signed and sealed this 20th day of February 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attest ing Officer Commissioner of Patents UNI ED STATES PATENT OFFlCE CERTIFICATE OF CORRECTION Patent No. 3,00lfl00 I I September 26 1961 James Bovaird Pow "corrected below.

Column 2 line 66 for "frame read frames column 3,, line 25 after "which" insert and line 3O for "the" first occurrence read an line 35,, for "with" read within line 57 for "lover" read lever same column 8 line 67 for "strip" read trip Signed and sealed this 20th day of February 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

